When President Trump finds himself in the middle of a controversy, he can turn to his lawyer for guidance. And that lawyer is White House counsel Don McGahn. NPR's Peter Overby introduces us to the man who interprets which ethics rules apply to the White House and when.

PETER OVERBY, BYLINE: Don McGahn was the lawyer for Trump's presidential campaign committee. Like his boss, he takes a dim view of too much regulation. And like his boss, he isn't shy about saying so. Consider this moment back in 2011, when McGahn was at the Federal Election Commission. He was arguing with another commissioner over the role of super PACs. Listen closely here.

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DON MCGAHN: You don't get to take matters in your own hands and take the book and just rip out the coordination rules, you know? And now my book's complete because we don't have the rules in there anymore.

OVERBY: And he tossed the ripped-out pages in the air. Brad Smith, head of the conservative Center for Competitive Politics, says McGahn worked hard to rein in FEC lawyers that he saw as overzealous.

BRAD SMITH: The vituperation he sometimes receives I think reflects the fact that he was very effective at, you know, what he sought to do, which was keeping the FEC within its constitutional and statutory role.

OVERBY: NPR asked to talk with McGahn for this story. The White House said he doesn't participate in interviews. Virginia Tech political scientist Karen Hult is co-author of an essay on the White House council rewritten every four years for the White House transition project.

KAREN HULT: Mr. McGahn is a certain kind of a lawyer who is known for taking very aggressive positions and outlining sometimes radical legal strategies.

OVERBY: Long before Don McGahn went to work for Trump, one of his uncles did. Patrick Paddy McGahn did legal work for Trump's move into the Atlantic City casino business. Trump also turned up in an FEC case that Don McGahn helped put an end to. In 2011, Trump was talking up running for president, as he did here on CNN.

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PRESIDENT DONALD TRUMP: I won't make a decision till June, but I will make a decision. And it may surprise people, frankly.

OVERBY: One of Trump's lawyers helped launch a website called Should Trump Run? FEC lawyers investigated whether Trump had to disclose his political spending. It became one of the many cases deep-sixed by the commission's Republicans. Led by McGahn, they said Trump clearly wasn't a candidate and the FEC lawyers had overreached. Craig Holman of the progressive watchdog group Public Citizen says the campaign and transition showed that McGahn and Trump are in sync when it comes to ethics.

CRAIG HOLMAN: I mean, if the White House is not going to be subject to conflict of interest codes, if the White House isn't going to have ethics training, what does that signal to the rest of the administration and the rest of the agencies?

OVERBY: But anybody in McGahn's job has to understand who the client is.

HULT: The White House counsel is the lawyer to the office of the presidency.

OVERBY: Again, Karen Hult, the expert on what White House counsels do.

HULT: That means not only the sitting president but the institution and the office itself, which makes it a very difficult balancing act for the White House counsel.

OVERBY: This winter, McGahn closed a different chapter of his life, his longtime gig playing lead guitar in a bar band on the mid-Atlantic shore circuit.

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SCOTT'S NEW BAND: Oh, yeah.

OVERBY: The band had its last gig New Year's Eve. Three weeks later, McGahn was working at the White House. Peter Overby, NPR News, Washington.